For me its situations, where in the past things haven't gone too well, so I have developed a fear and anxiety about the situation. So really, any group situation will send me in a spiral, doesn't matter who its with or where it is, if the group increases beyond 3 people, it becomes a nightmare. I have built it up so much in my mind, layers and layers over the years. Its a shame around the situation, a feeling of being wrong or unworthy. And is definitely is a shame! Hiding a stammer should not be the goal. The avoidance and shame will make it worse. Self-fulfilling prophesy is a good term to use.